Methods for manufacturing bulked continuous filament

ABSTRACT

A method for manufacturing bulked continuous carpet filament, the method comprising: (1) reducing a chamber pressure within a chamber to below about 5 millibars; (2) after reducing the chamber pressure to below about 5 millibars, providing a polymer melt to the chamber; (3) separating the polymer melt into at least eight streams; (4) while the at least eight streams of the polymer melt are within the chamber, exposing the at least eight streams of the polymer melt to the chamber pressure of below about 5 millibars; (5) after exposing the at least eight streams of the polymer melt to the chamber pressure of below about 5 millibars, recombining the at least eight streams into a single polymer stream; and (6) forming polymer from the single polymer stream into bulked continuous carpet filament.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/041,442, filed Jul. 20, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/204,645, filed Jul. 7, 2016, now U.S. Pat. No.10,124,513, issued Nov. 13, 2018, which is a continuation of U.S. patentapplication Ser. No. 14/256,261, filed Apr. 18, 2014, now U.S. Pat. No.9,409,363, issued Aug. 9, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/892,713, filed May 13, 2013, now U.S. Pat. No.9,550,338, issued Jan. 24, 2017, which is a divisional of U.S. patentapplication Ser. No. 13/721,955, filed Dec. 20, 2012, now U.S. Pat. No.8,597,553, issued Dec. 3, 2013, which claims priority from U.S.Provisional Patent Application Ser. No. 61/654,016, filed May 31, 2012,the entire disclosures of which are hereby incorporated by reference intheir entirety.

BACKGROUND

Because pure virgin PET polymer is more expensive than recycled PETpolymer, and because of the environmental benefits associated with usingrecycled polymer, it would be desirable to be able to produce bulkedcontinuous carpet filament from 100% recycled PET polymer (e.g., PETpolymer from post-consumer PET bottles).

SUMMARY

A method of manufacturing bulked continuous carpet filament, in variousembodiments, comprises providing a multi-screw extruder. In particularembodiments, the multi-screw extruder comprises: (A) a housing thatdefines at least six satellite screw barrels; (B) at least six satellitescrews each mounted within a respective one of the at least sixsatellite screw barrels and mounted to rotate about a respective centralaxis of each of the at least six satellite screws; and (C) a pressureregulation system that is adapted to maintain a pressure within each ofthe respective satellite screw barrels between about 0.5 millibars andabout 5 millibars. In particular embodiments, the method furthercomprises: (A) using the pressure regulation system to reduce a pressurewithin the at least six satellite screw barrels to between about 0.5millibars and about 5 millibars; (B) while maintaining the pressurewithin the at least six satellite screw barrels between about 0.5millibars and about 5 millibars, passing a melt comprising recycledpolymer through the multi-screw extruder so that at least a portion ofthe melt is fed through each of the at least six satellite screws; and(C) after the step of passing the melt of recycled polymer through themulti-screw extruder, forming the recycled polymer into bulkedcontinuous carpet filament.

An extruder for use in extruding a polymer melt, according to particularembodiments, comprises at least: (1) a first satellite screw extrudercomprising a first satellite screw that is mounted to rotate about acentral axis of the first satellite screw; (2) a second satellite screwextruder comprising a second satellite screw that is mounted to rotateabout a central axis of the second satellite screw; and (3) a pressureregulation system that is adapted to maintain a pressure within thefirst and second satellite screw extruders below a pressure of about 5millibars as the polymer melt passes through the first and second screwextruders.

A bulked continuous carpet filament, according to various embodiments,consists essentially of a recycled polymer.

A method of manufacturing carpet filament, according to particularembodiments, comprises the steps of: (A) washing a group of polymerflakes to remove at least a portion of one or more contaminants from asurface of the flakes, the group of flakes comprising a first pluralityof flakes that consist essentially of PET and a second plurality offlakes that do not consist essentially of PET; (B) after the step ofwashing the first plurality of flakes: (i) scanning the washed group offlakes to identify the second plurality of flakes, and (ii) separatingthe second plurality of flakes from the first plurality of flakes; (C)melting the second plurality of flakes to produce a polymer melt; (D)providing an extruder that extrudes material in a plurality of differentextrusion streams; (E) reducing a pressure within the extruder to belowabout 5 millibars; (F) while maintaining the pressure within theextruder below about 5 millibars, passing the polymer melt through theextruder so that the polymer melt is divided into at least eightextrusion streams, each having a pressure below about 5 millibars; (G)after passing the polymer melt through the extruder, forming therecycled polymer into bulked continuous carpet filament.

A method of manufacturing bulked continuous carpet filament, the methodcomprising: (1) providing a polymer melt from an extruder to a chamber;(2) separating the polymer melt from the extruder into at least eightstreams such that each stream is at least partially exposed to aninterior of the chamber and such that a respective surface area of eachof the at least eight streams is exposed to a chamber pressure withinthe chamber, the chamber pressure being below about 5 millibars; (3)after the at least eight streams are exposed to the chamber pressure,recombining the at least eight streams into a single polymer stream; and(4) forming polymer from the single polymer stream into bulkedcontinuous carpet filament.

A method for manufacturing bulked continuous carpet filament, the methodcomprising: (1) providing an extruder; (2) providing a plurality ofpolymer flakes to the extruder; (3) melting the plurality of polymerflakes within the extruder to create a polymer melt; (4) transferringthe polymer melt to an interior of a chamber; (4) increasing a surfacearea of the polymer melt exposed to the interior of the chamberutilizing at least eight streams of the polymer melt; (5) reducing apressure within the chamber to reach a chamber pressure of below about 5millibars; (6) exposing the at least eight streams of the polymer meltto the chamber pressure of below about 5 millibars while the at leasteight streams of the polymer melt are in the chamber; (7) after exposingthe at least eight streams of the polymer melt to the chamber pressureof below about 5 millibars, recombining the at least eight streams intoa single polymer stream; and (8) forming polymer from the single polymerstream into bulked continuous carpet filament.

A method for manufacturing bulked continuous carpet filament, the methodcomprising: (1) reducing a chamber pressure within a chamber to belowabout 5 millibars; (2) after reducing the chamber pressure to belowabout 5 millibars, providing a polymer melt to the chamber; (3)separating the polymer melt into at least eight streams; (4) while theat least eight streams of the polymer melt are within the chamber,exposing the at least eight streams of the polymer melt to the chamberpressure of below about 5 millibars; (5) after exposing the at leasteight streams of the polymer melt to the chamber pressure of below about5 millibars, recombining the at least eight streams into a singlepolymer stream; and (6) forming polymer from the single polymer streaminto bulked continuous carpet filament.

BRIEF DESCRIPTION OF THE DRAWINGS

Having described various embodiments in general terms, reference willnow be made to the accompanying drawings, which are not necessarilydrawn to scale, and wherein:

FIG. 1 depicts a process flow, according to a particular embodiment, formanufacturing bulked continuous carpet filament.

FIG. 2 is a perspective view of an MRS extruder that is suitable for usein the process of FIG. 1.

FIG. 3 is a cross-sectional view of an exemplary MRS section of the MRSextruder of FIG. 2.

FIG. 4 depicts a process flow depicting the flow of polymer through anMRS extruder and filtration system according to a particular embodiment.

FIG. 5 is a high-level flow chart of a method, according to variousembodiments, of manufacturing bulked continuous carpet filament.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Various embodiments will now be described in greater detail. It shouldbe understood that the invention may be embodied in many different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. Like numbers refer to likeelements throughout.

I. Overview

New processes for making fiber from recycled polymer (e.g., recycled PETpolymer) are described below. In various embodiments, this new process:(1) is more effective than earlier processes in removing contaminatesand water from the recycled polymer; and/or (2) does not require thepolymer to be melted and cooled as many times as in earlier processes.In at least one embodiment, the improved process results in a recycledPET polymer having a polymer quality that is high enough that the PETpolymer may be used in producing bulked continuous carpet filament from100% recycled PET content (e.g., 100% from PET obtained from previouslyused PET bottles). In particular embodiments, the recycled PET polymerhas an intrinsic viscosity of at least about 0.79 dL/g (e.g., of betweenabout 0.79 dL/g and about 1.00 dL/g).

II. More Detailed Discussion

A BCF (bulked continuous filament) manufacturing process, according to aparticular embodiment, may generally be broken down into three steps:(1) preparing flakes of PET polymer from post-consumer bottles for usein the process; (2) passing the flakes through an extruder that meltsthe flakes and purifies the resulting PET polymer; and (3) feeding thepurified polymer into a spinning machine that turns the polymer intofilament for use in manufacturing carpets. These three steps aredescribed in greater detail below.

Step 1: Preparing Flakes of PET Polymer from Post-Consumer Bottles

In a particular embodiment, the step of preparing flakes of PET polymerfrom post-consumer bottles comprises: (A) sorting post-consumer PETbottles and grinding the bottles into flakes; (B) washing the flakes;and (C) identifying and removing any impurities or impure flakes.

A. Sorting Post-Consumer PET Bottles and Grinding the Bottles intoFlakes

In particular embodiments, bales of clear and mixed colored recycledpost-consumer (e.g., “curbside”) PET bottles (or other containers)obtained from various recycling facilities make-up the post-consumer PETcontainers for use in the process. In other embodiments, the source ofthe post-consumer PET containers may be returned ‘deposit’ bottles(e.g., PET bottles whose price includes a deposit that is returned to acustomer when the customer returns the bottle after consuming thebottle's contents). The curbside or returned “post-consumer” or“recycled” containers may contain a small level of non-PET contaminates.The contaminants in the containers may include, for example, non-PETpolymeric contaminants (e.g., PVC, PLA, PP, PE, PS, PA, etc.), metal(e.g., ferrous and non-ferrous metal), paper, cardboard, sand, glass orother unwanted materials that may find their way into the collection ofrecycled PET. The non-PET contaminants may be removed from the desiredPET components, for example, through one or more of the variousprocesses described below.

In particular embodiments, smaller components and debris (e.g.,components and debris greater than 2 inches in size) are removed fromthe whole bottles via a rotating trammel. Various metal removal magnetsand eddy current systems may be incorporated into the process to removeany metal contaminants. Near Infra-Red optical sorting equipment such asthe NRT Multi Sort IR machine from Bulk Handling Systems Company ofEugene, Oreg., or the Spyder IR machine from National RecoveryTechnologies of Nashville, Tenn., may be utilized to remove any loosepolymeric contaminants that may be mixed in with the PET flakes (e.g.,PVC, PLA, PP, PE, PS, and PA). Additionally, automated X-ray sortingequipment such as a VINYLCYCLE machine from National RecoveryTechnologies of Nashville, Tenn. may be utilized to remove remaining PVCcontaminants.

In particular embodiments, a binary segregation of the clear materialsfrom the colored materials is achieved using automated color sortingequipment equipped with a camera detection system (e.g., an Multisort ESmachine from National Recovery Technologies of Nashville, Tenn.). Invarious embodiments, manual sorters are stationed at various points onthe line to remove contaminants not removed by the sorter and anycolored bottles. In particular embodiments, the sorted material is takenthrough a granulation step (e.g., using a 50B Granulator machine fromCumberland Engineering Corporation of New Berlin, Wis.) to size reduce(e.g., grind) the bottles down to a size of less than one half of aninch. In various embodiments, the bottle labels are removed from theresultant “dirty flake” (e.g., the PET flakes formed during thegranulation step) via an air separation system prior to entering thewash process.

B. Washing the Flakes

In particular embodiments, the “dirty flake” is then mixed into a seriesof wash tanks. As part of the wash process, in various embodiments, anaqueous density separation is utilized to separate the olefin bottlecaps (which may, for example, be present in the “dirty flake” asremnants from recycled PET bottles) from the higher specific gravity PETflakes. In particular embodiments, the flakes are washed in a heatedcaustic bath to about 190 degrees Fahrenheit. In particular embodiments,the caustic bath is maintained at a concentration of between about 0.6%and about 1.2% sodium hydroxide. In various embodiments, soapsurfactants as well as defoaming agents are added to the caustic bath,for example, to further increase the separation and cleaning of theflakes. A double rinse system then washes the caustic from the flakes.

In various embodiments, the flake is centrifugally dewatered and thendried with hot air to at least substantially remove any surfacemoisture. The resultant “clean flake” is then processed through anelectrostatic separation system (e.g., an electrostatic separator fromCarpco, Inc. of Jacksonville, Fla.) and a flake metal detection system(e.g., an MSS Metal Sorting System) to further remove any metalcontaminants that remain in the flake. In particular embodiments, an airseparation step removes any remaining label from the clean flake. Invarious embodiments, the flake is then taken through a flake colorsorting step (e.g., using an OPTIMIX machine from TSM Control Systems ofDundalk, Ireland) to remove any remaining color contaminants remainingin the flake. In various embodiments, an electro-optical flake sorterbased at least in part on Raman technology (e.g., a Powersort 200 fromUnisensor Sensorsysteme GmbH of Karlsruhe, Germany) performs the finalpolymer separation to remove any non-PET polymers remaining in theflake. This step may also further remove any remaining metalcontaminants and color contaminants.

In various embodiments, the combination of these steps deliverssubstantially clean (e.g., clean) PET bottle flake comprising less thanabout 50 parts per million PVC (e.g., 25 ppm PVC) and less than about 15parts per million metals for use in the downstream extrusion processdescribed below.

C. Identifying and Removing Impurities and Impure Flakes

In particular embodiments, after the flakes are washed, they are feddown a conveyor and scanned with a high-speed laser system 300. Invarious embodiments, particular lasers that make up the high-speed lasersystem 300 are configured to detect the presence of particularcontaminates (e.g., PVC or Aluminum). Flakes that are identified as notconsisting essentially of PET may be blown from the main stream offlakes with air jets. In various embodiments, the resulting level ofnon-PET flakes is less than 25 ppm.

In various embodiments, the system is adapted to ensure that the PETpolymer being processed into filament is substantially free of water(e.g., entirely free of water). In a particular embodiment, the flakesare placed into a pre-conditioner for between about 20 and about 40minutes (e.g., about 30 minutes) during which the pre-conditioner blowsthe surface water off of the flakes. In particular embodiments,interstitial water remains within the flakes. In various embodiments,these “wet” flakes (e.g., flakes comprising interstitial water) may thenbe fed into an extruder (e.g., as described in Step 2 below), whichincludes a vacuum setup designed to remove—among other things—theinterstitial water that remains present in the flakes following thequick-drying process described above.

Step 2: Using an Extrusion System to Melt and Purify PET Flakes

In particular embodiments, an extruder is used to turn the wet flakesdescribed above into a molten recycled PET polymer and to perform anumber of purification processes to prepare the polymer to be turnedinto BCF for carpet. As noted above, in various embodiments, after STEP1 is complete, the recycled PET polymer flakes are wet (e.g., surfacewater is substantially removed (e.g., fully removed) from the flakes,but interstitial water remains in the flakes). In particularembodiments, these wet flakes are fed into a Multiple Rotating Screw(“MRS”) extruder 400. In other embodiments, the wet flakes are fed intoany other suitable extruder (e.g., a twin screw extruder, a multiplescrew extruder, a planetary extruder, or any other suitable extrusionsystem). An exemplary MRS Extruder 400 is shown in FIGS. 2 and 3. Aparticular example of such an MRS extruder is described in U.S.Published Patent Application 2005/0047267, entitled “Extruder forProducing Molten Plastic Materials”, which was published on Mar. 3,2005, and which is hereby incorporated herein by reference.

As may be understood from this figure, in particular embodiments, theMRS extruder includes a first single-screw extruder section 410 forfeeding material into an MRS section 420 and a second single-screwextruder section 440 for transporting material away from the MRSsection.

In various embodiments, the wet flakes are fed directly into the MRSextruder 400 substantially immediately (e.g., immediately) following thewashing step described above (e.g., without drying the flakes orallowing the flakes to dry). In particular embodiments, a system thatfeeds the wet flakes directly into the MRS Extruder 400 substantiallyimmediately (e.g., immediately) following the washing step describedabove may consume about 20% less energy than a system that substantiallyfully pre-dries the flakes before extrusion (e.g., a system thatpre-dries the flakes by passing hot air over the wet flakes for aprolonged period of time). In various embodiments, a system that feedsthe wet flakes directly into the MRS Extruder 400 substantiallyimmediately (e.g., immediately) following the washing step describedabove avoids the need to wait a period of time (e.g., up to eight hours)generally required to fully dry the flakes (e.g., remove all of thesurface and interstitial water from the flakes).

FIG. 4 depicts a process flow that illustrates the various processesperformed by the MRS Extruder 400 in a particular embodiment. In theembodiment shown in this figure, the wet flakes are first fed throughthe MRS extruder's first single-screw extruder section 410, which may,for example, generate sufficient heat (e.g., via shearing) to at leastsubstantially melt (e.g., melt) the wet flakes.

The resultant polymer melt (e.g., comprising the melted flakes), invarious embodiments, is then fed into the extruder's MRS section 420, inwhich the extruder separates the melt flow into a plurality of differentstreams (e.g., 4, 6, 8, or more streams) through a plurality of openchambers. FIG. 3 shows a detailed cutaway view of an MRS Section 420according to a particular embodiment. In particular embodiments, such asthe embodiment shown in this figure, the MRS Section 420 separates themelt flow into eight different streams, which are subsequently fedthrough eight satellite screws 425A-H. As may be understood from FIG. 2,in particular embodiments, these satellite screws are substantiallyparallel (e.g., parallel) to one other and to a primary screw axis ofthe MRS Machine 400.

In the MRS section 420, in various embodiments, the satellite screws425A-H may, for example, rotate faster than (e.g., about four timesfaster than) in previous systems. As shown in FIG. 3, in particularembodiments: (1) the satellite screws 425A-H are arranged within asingle screw drum 428 that is mounted to rotate about its central axis;and (2) the satellite screws 425A-H are configured to rotate in adirection that is opposite to the direction in which the single screwdrum rotates 428. In various other embodiments, the satellite screws425A-H and the single screw drum 428 rotate in the same direction. Inparticular embodiments, the rotation of the satellite screws 425A-H isdriven by a ring gear. Also, in various embodiments, the single screwdrum 428 rotates about four times faster than each individual satellitescrew 425A-H. In certain embodiments, the satellite screws 425A-H rotateat substantially similar (e.g., the same) speeds.

In various embodiments, as may be understood from FIG. 4, the satellitescrews 425A-H are housed within respective extruder barrels, which may,for example be about 30% open to the outer chamber of the MRS section420. In particular embodiments, the rotation of the satellite screws425A-H and single screw drum 428 increases the surface exchange of thepolymer melt (e.g., exposes more surface area of the melted polymer tothe open chamber than in previous systems). In various embodiments, theMRS section 420 creates a melt surface area that is, for example,between about twenty and about thirty times greater than the meltsurface area created by a co-rotating twin screw extruder. In aparticular embodiment, the MRS section 420 creates a melt surface areathat is, for example, about twenty five times greater than the meltsurface area created by a co-rotating twin screw extruder

In various embodiments, the MRS extruder's MRS Section 420 is fittedwith a Vacuum Pump 430 that is attached to a vacuum attachment portion422 of the MRS section 420 so that the Vacuum Pump 430 is incommunication with the interior of the MRS section via a suitableopening 424 in the MRS section's housing. In still other embodiments,the MRS Section 420 is fitted with a series of Vacuum Pumps. Inparticular embodiments, the Vacuum Pump 430 is configured to reduce thepressure within the interior of the MRS Section 420 to a pressure thatis between about 0.5 millibars and about 5 millibars. In particularembodiments, the Vacuum Pump 430 is configured to reduce the pressure inthe MRS Section 420 to less than about 1.5 millibars (e.g., about 1millibar or less). The low-pressure vacuum created by the Vacuum Pump430 in the MRS Section 420 may remove, for example: (1) volatileorganics present in the melted polymer as the melted polymer passesthrough the MRS Section 420; and/or (2) at least a portion of anyinterstitial water that was present in the wet flakes when the wetflakes entered the MRS Extruder 400. In various embodiments, thelow-pressure vacuum removes substantially all (e.g., all) of the waterand contaminants from the polymer stream.

In a particular example, the Vacuum Pump 430 comprises three mechanicallobe vacuum pumps (e.g., arranged in series) to reduce the pressure inthe chamber to a suitable level (e.g., to a pressure of about 1.0millibar). In other embodiments, rather than the three mechanical lobevacuum pump arrangement discussed above, the Vacuum Pump 430 includes ajet vacuum pump fit to the MRS extruder. In various embodiments, the jetvacuum pump is configured to achieve about 1 millibar of pressure in theinterior of the MRS section 420 and about the same results describedabove regarding a resulting intrinsic viscosity of the polymer melt. Invarious embodiments, using a jet vacuum pump can be advantageous becausejet vacuum pumps are steam powered and therefore substantiallyself-cleaning (e.g., self-cleaning), thereby reducing the maintenancerequired in comparison to mechanical lobe pumps (which may, for example,require repeated cleaning due to volatiles coming off and condensing onthe lobes of the pump). In a particular embodiment, the Vacuum Pump 430is a jet vacuum pump is made by Arpuma GmbH of Bergheim, Germany.

In particular embodiments, after the molten polymer is run the throughthe multi-stream MRS Section 420, the streams of molten polymer arerecombined and flow into the MRS extruder's second single screw section440. In various embodiments, the single stream of molten polymer is nextrun through a filtration system 450 that includes at least one filter.In a particular embodiment, the filtration system 450 includes twolevels of filtration (e.g., a 40 micron screen filter followed by a 25micron screen filter). Although, in various embodiments, water andvolatile organic impurities are removed during the vacuum process asdiscussed above, particulate contaminates such as, for example, aluminumparticles, sand, dirt, and other contaminants may remain in the polymermelt. Thus, this filtration step may be advantageous in removingparticulate contaminates (e.g., particulate contaminates that were notremoved in the MRS Section 420).

In particular embodiments, a viscosity sensor 460 (see FIG. 4) is usedto sense the melt viscosity of the molten polymer stream following itspassage through the filtration system 450. In various embodiments, theviscosity sensor 460, measures the melt viscosity of the stream, forexample, by measuring the stream's pressure drop across a known area. Inparticular embodiments, in response to measuring an intrinsic viscosityof the stream that is below a predetermined level (e.g., below about 0.8g/dL), the system may: (1) discard the portion of the stream with lowintrinsic viscosity; and/or (2) lower the pressure in the MRS Section420 in order to achieve a higher intrinsic viscosity in the polymermelt. In particular embodiments, decreasing the pressure in the MRSSection 420 is executed in a substantially automated manner (e.g.,automatically) using the viscosity sensor in a computer-controlledfeedback control loop with the vacuum section 430.

In particular embodiments, removing the water and contaminates from thepolymer improves the intrinsic viscosity of the recycled PET polymer byallowing polymer chains in the polymer to reconnect and extend the chainlength. In particular embodiments, following its passage through the MRSSection 420 with its attached Vacuum Pump 430, the recycled polymer melthas an intrinsic viscosity of at least about 0.79 dL/g (e.g., of betweenabout 0.79 dL/g and about 1.00 dL/g). In particular embodiments, passagethrough the low pressure MRS Section 420 purifies the recycled polymermelt (e.g., by removing the contaminants and interstitial water) andmakes the recycled polymer substantially structurally similar to (e.g.,structurally the same as) pure virgin PET polymer. In particularembodiments, the water removed by the vacuum includes both water fromthe wash water used to clean the recycled PET bottles as describedabove, as well as from unreacted water generated by the melting of thePET polymer in the single screw heater 410 (e.g., interstitial water).In particular embodiments, the majority of water present in the polymeris wash water, but some percentage may be unreacted water.

In particular embodiments, the resulting polymer is a recycled PETpolymer (e.g., obtained 100% from post-consumer PET products, such asPET bottles or containers) having a polymer quality that is suitable foruse in producing PET carpet filament using substantially only (e.g.,only) PET from recycled PET products.

Step 3: Purified PET Polymer Fed into Spinning Machine to be Turned intoCarpet Yarn

In particular embodiments, after the recycled PET polymer has beenextruded and purified by the above-described extrusion process, theresulting molten recycled PET polymer is fed directly into a BCF (or“spinning”) machine 500 that is configured to turn the molten polymerinto bulked continuous filament. For example, in various embodiments,the output of the MRS extruder 400 is connected substantially directly(e.g., directly) to the input of the spinning machine 500 so that moltenpolymer from the extruder is fed directly into the spinning machine 500.This process may be advantageous because molten polymer may, in certainembodiments, not need to be cooled into pellets after extrusion (as itwould need to be if the recycled polymer were being mixed with virginPET polymer). In particular embodiments, not cooling the recycled moltenpolymer into pellets serves to avoid potential chain scission in thepolymer that might lower the polymer's intrinsic viscosity.

In particular embodiments, the spinning machine 500 extrudes moltenpolymer through small holes in a spinneret in order to produce carpetyarn filament from the polymer. In particular embodiments, the moltenrecycled PET polymer cools after leaving the spinneret. The carpet yarnis then taken up by rollers and ultimately turned into filaments thatare used to produce carpet. In various embodiments, the carpet yarnproduced by the spinning machine 500 may have a tenacity between about 3gram-force per unit denier (gf/den) and about 9 gf/den. In particularembodiments, the resulting carpet yarn has a tenacity of at least about3 gf/den.

In particular embodiments, the spinning machine 500 used in the processdescribed above is the Sytec One spinning machine manufactured byOerlika Neumag of Neumuenster, Germany. The Sytec One machine may beespecially adapted for hard-to-run fibers, such as nylon orsolution-dyed fibers, where the filaments are prone to breakage duringprocessing. In various embodiments, the Sytec One machine keeps the runsdownstream of the spinneret as straight as possible, uses only onethreadline, and is designed to be quick to rethread when there arefilament breaks.

Although the example described above describes using the Sytec Onespinning machine to produce carpet yarn filament from the polymer, itshould be understood that any other suitable spinning machine may beused. Such spinning machines may include, for example, any suitableone-threadline or three-threadline spinning machine made by OerlikaNeumag of Neumuenster, Germany or any other company.

In various embodiments, the improved strength of the recycled PETpolymer generated using the process above allows it to be run at higherspeeds through the spinning machine 500 than would be possible usingpure virgin PET polymer. This may allow for higher processing speedsthan are possible when using virgin PET polymer.

Summary of Exemplary Process

FIG. 5 provides a high-level summary of the method of manufacturingbulked continuous filament described above. As shown in the figure, themethod begins at Step 602, where recycled PET bottles are ground into agroup of flakes. Next, at Step 604, the group of flakes is washed toremove contaminants from the flakes' respective outer surfaces. Next, atStep 606, the group of flakes is scanned (e.g., using one or more of themethods discussed above) to identify impurities, including impureflakes. These impurities, and impure flakes, are then removed from thegroup of flakes.

Next, at Step 608, the group of flakes is passed through an MRS extruderwhile maintaining the pressure within an MRS portion of the extruderbelow about 1.5 millibars. At Step 610, the resulting polymer melt ispassed through at least one filter having a micron rating of less thanabout 50 microns. Finally, at Step 612, the recycled polymer is formedinto bulked continuous carpet filament, which may be used in producingcarpet. The method then ends at Step 614.

Alternative Embodiments

In particular embodiments, the system may comprise alternativecomponents or perform alternative processes in order to producesubstantially continuous BCF from 100% recycled PET, or other recycledpolymer. Exemplary alternatives are discussed below.

Non-MRS Extrusion System

In particular embodiments, the process may utilize a polymer flowextrusion system other than the MRS Extruder described above. Thealternative extrusion system may include for example, a twin screwextruder, a multiple screw extruder, a planetary extruder, or any othersuitable extrusion system. In a particular embodiment, the process mayinclude a plurality of any combination of any suitable conical screwextruders (e.g., four twin screw extruders, three multiple screwextruders, etc.).

Making Carpet Yarn from 100% Recycled Carpet

In particular embodiments, the process described above may be adaptedfor processing and preparing old carpet (or any other suitablepost-consumer product) to produce new carpet yarn comprising 100%recycled carpet. In such embodiments, the process would begin bygrinding and washing recycled carpet rather than recycled PET bottles.In various embodiments where old carpet is converted into new carpetyarn comprising 100% recycled carpet, the process may compriseadditional steps to remove additional materials or impurities that maybe present in recycled carpet that may not be present in recycled PETbottles (e.g., carpet backing, adhesive, etc.).

Other Sources of Recycled PET

In various embodiments, the process described above is adapted forprocessing recycled PET from any suitable source (e.g., sources otherthan recycled bottles or carpet) to produce new carpet yarn comprising100% recycled PET.

CONCLUSION

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. For example, although the vacuum systemdiscussed above is described as being configured to maintain thepressure in the open chambers of the MRS extruder to about 1 mbar, inother embodiments, the vacuum system may be adapted to maintain thepressure in the open chambers of the MRS extruder at pressures greaterthan, or less than, 1 mbar. For example, the vacuum system may beadapted to maintain this pressure at between about 0.5 mbar and about1.2 mbar.

Similarly, although various embodiments of the systems described abovemay be adapted to produce carpet filament from substantially onlyrecycled PET (so the resulting carpet filament would comprise, consistof, and/or consist essentially of recycled PET), in other embodiments,the system may be adapted to produce carpet filament from a combinationof recycled PET and virgin PET. The resulting carpet filament may, forexample, comprise, consist of, and/or consist essentially of betweenabout 80% and about 100% recycled PET, and between about 0% and about20% virgin PET.

Also, while various embodiments are discussed above in regard toproducing carpet filament from PET, similar techniques may be used toproduce carpet filament from other polymers. Similarly, while variousembodiments are discussed above in regard to producing carpet filamentfrom PET, similar techniques may be used to produce other products fromPET or other polymers.

In addition, it should be understood that various embodiments may omitany of the steps described above or add additional steps.

In light of the above, it is to be understood that the invention is notto be limited to the specific embodiments disclosed and thatmodifications and other embodiments are intended to be included withinthe scope of the appended claims. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor the purposes of limitation.

I claim:
 1. A method of manufacturing bulked continuous carpet filament,the method comprising: providing a polymer melt from an extruder to achamber; separating the polymer melt from the extruder into at leasteight streams such that each stream is at least partially exposed to aninterior of the chamber and such that a respective surface area of eachof the at least eight streams is exposed to a chamber pressure withinthe chamber, the chamber pressure being below about 5 millibars; afterthe at least eight streams are exposed to the chamber pressure,recombining the at least eight streams into a single polymer stream; andforming polymer from the single polymer stream into bulked continuouscarpet filament.
 2. The method of claim 1, wherein the chamber pressureis below about 1.5 millibars.
 3. The method of claim 1, wherein thechamber pressure is below about 1 millibar.
 4. The method of claim 1,wherein the chamber pressure is between about 0.5 millibars and about 5millibars.
 5. The method of claim 1, wherein the chamber pressure isbetween about 0.5 millibars and about 1.2 millibars.
 6. The method ofclaim 1, further comprising: measuring an intrinsic viscosity of thesingle polymer stream; and in response to determining that the intrinsicviscosity of the single polymer stream is below a predetermined level,substantially automatically lowering the chamber pressure in order toachieve a higher intrinsic viscosity within the polymer melt.
 7. Themethod of claim 1, wherein the polymer melt is derived, at least inpart, from polyethylene terephthalate (PET) flakes that are derived fromrecycled PET bottles.
 8. The method of claim 7, wherein the recycled PETbottles are post-consumer, curbside PET bottles.
 9. A method formanufacturing bulked continuous carpet filament, the method comprising:providing an extruder; providing a plurality of polymer flakes to theextruder; melting the plurality of polymer flakes within the extruder tocreate a polymer melt; transferring the polymer melt to an interior of achamber; increasing a surface area of the polymer melt exposed to theinterior of the chamber utilizing at least eight different streams ofthe polymer melt; reducing a pressure within the chamber to reach achamber pressure of below about 5 millibars; exposing the at least eightstreams of the polymer melt to the chamber pressure of below about 5millibars while the at least eight streams of the polymer melt are inthe chamber; after exposing the at least eight streams of the polymermelt to the chamber pressure of below about 5 millibars, recombining theat least eight streams into a single polymer stream; and forming polymerfrom the single polymer stream into bulked continuous carpet filament.10. The method of claim 9, wherein the step of recombining the at leasteight streams into a single polymer stream comprises recombining the atleast eight streams into a single polymer stream via a single screwextruder.
 11. The method of claim 10, wherein the single screw extruderis used to transport polymer within the single polymer stream away fromthe chamber.
 12. The method of claim 9, wherein the at least eightstreams of the polymer melt comprise more than 8 streams of polymermelt.
 13. The method of claim 9, wherein exposing the at least eightstreams of the polymer melt to the chamber pressure while the at leasteight streams of the polymer melt are in the chamber comprises exposingthe at least eight streams of the polymer melt to a chamber pressurethat is below about 1.5 millibars.
 14. The method of claim 9, whereinexposing the at least eight streams of the polymer melt to the chamberpressure while the at least eight streams of the polymer melt are in thechamber comprises exposing the at least eight streams of the polymermelt to a chamber pressure that is below about 1 millibar.
 15. Themethod of claim 9, wherein exposing the at least eight streams of thepolymer melt to the chamber pressure while the at least eight streams ofthe polymer melt are in the chamber comprises exposing the at leasteight streams of the polymer melt to a chamber pressure that is betweenabout 0.5 millibars and about 5 millibars.
 16. The method of claim 9,wherein exposing the at least eight streams of the polymer melt to thechamber pressure while the at least eight streams of the polymer meltare in the chamber comprises exposing the at least eight streams of thepolymer melt to a chamber pressure that is between about 0.5 millibarand about 1.2 millibars.
 17. The method of claim 9, further comprising:determining an intrinsic viscosity of the single polymer stream; and inresponse to determining that the intrinsic viscosity of the singlepolymer stream is below a predetermined level, substantiallyautomatically lowering the chamber pressure.
 18. The method of claim 17,wherein the predetermined level is about 0.8 g/dL.
 19. The method ofclaim 9, wherein the plurality of polymer flakes comprises polyethyleneterephthalate (PET) flakes derived from recycled PET bottles.
 20. Themethod of claim 9, wherein forming polymer from the single polymerstream into bulked continuous carpet filament comprises forming polymerfrom the single polymer stream into bulked continuous carpet filamentthat comprises between about 80% and about 100% recycled PET.
 21. Amethod for manufacturing bulked continuous carpet filament, the methodcomprising: reducing a chamber pressure within a chamber to below about5 millibars; after reducing the chamber pressure to below about 5millibars, providing a polymer melt to the chamber; separating thepolymer melt into at least eight streams; while the at least eightstreams of the polymer melt are within the chamber, exposing the atleast eight streams of the polymer melt to the chamber pressure of belowabout 5 millibars; after exposing the at least eight streams of thepolymer melt to the chamber pressure of below about 5 millibars,recombining the at least eight streams into a single polymer stream; andforming polymer from the single polymer stream into bulked continuouscarpet filament.
 22. The method of claim 21, wherein exposing the atleast eight streams of the polymer melt to the chamber pressure whilethe at least eight streams of the polymer melt are within the chambercomprises exposing the at least eight streams of the polymer melt to achamber pressure that is below about 1.5 millibars.
 23. The method ofclaim 21, wherein exposing the at least eight streams of the polymermelt to the chamber pressure while the at least eight streams of thepolymer melt are within the chamber comprises exposing the at leasteight streams of the polymer melt to a chamber pressure that is belowabout 1 millibar.
 24. The method of claim 21, wherein exposing the atleast eight streams of the polymer melt to the chamber pressure whilethe at least eight streams of the polymer melt are within the chambercomprises exposing the at least eight streams of the polymer melt to achamber pressure that is between about 0.5 millibars and about 5millibars.
 25. The method of claim 21, wherein exposing the at leasteight streams of the polymer melt to the chamber pressure while the atleast eight streams of the polymer melt are within the chamber comprisesexposing the at least eight streams of the polymer melt to a chamberpressure that is between about 0.5 millibar and about 1.2 millibars. 26.The method of claim 21, further comprising: determining an intrinsicviscosity of the single polymer stream; and in response to determiningthat the intrinsic viscosity of the single polymer stream is below apredetermined level, lowering the pressure in the chamber in asubstantially automated manner via a computer-controlled feedbackcontrol loop.
 27. The method of claim 21, further comprising meltingpolyethylene terephthalate (PET) flakes derived from recycled PETbottles to produce the polymer melt.
 28. The method of claim 21, whereinforming polymer from the single polymer stream into bulked continuouscarpet filament comprises forming polymer from the single polymer streaminto bulked continuous carpet filament that comprises between about 80%and about 100% recycled PET.
 29. The method of claim 21, wherein thestep of recombining the at least eight streams into a single polymerstream comprises recombining the at least eight streams into a singlepolymer stream via a single screw extruder.
 30. The method of claim 29,wherein the single screw extruder is used to transport polymer withinthe single polymer stream away from the chamber.